class_docstr: Registration map from python AST node type str to methods of conversion
  between python AST node and doc AST node.
  
  Parameters
  ----------
  _inst : typing.Optional["Registry"]
      The instance of Registry.
  
  table : typing.Dict[str, Entry]
      The registration map from python AST node type str to methods of conversion
      between python AST node and doc AST node.
code: def __init__(self):
      self.table = defaultdict(Entry)
  
imports: import ast
  import inspect
  import sys
  import typing
  from collections import defaultdict
  from .None import doc_core
  from .doc_core import *
label_desc: Use image node_id 1 to create a new Registry object  with example: obj = Registry()